Flexible building material compounds

ABSTRACT

Flexible building compositions are provided which are based on mineral binders and vinylester-ethylene mixed polymers which are stabilized by protective colloids and prepared by radical aqueous emulsion polymerization.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to flexible, polymer-modified buildingcompositions and also the use of vinyl ester ethylene copolymersstabilized by protective colloids for flexibilizing buildingcompositions.

2. Background Art

For certain applications in the building sector, for example in sealingslurries or for building adhesives, highly flexible concrete or mortarmixtures are required. In accordance with standards, for example insealing slurries, use is made of mortar mixtures which are modified withemulsifier-stabilized acrylate dispersions. WO-A 92/07804 (AU-A 9186679)describes binders for flexibilizing building materials, which binderscomprise mixtures of polyester resin and styrene-acrylatecopolymer--emulsion. EP-A 558980 (U.S. Pat. No. 5,348,993) disclosesemulsifier-stabilized styrene-acrylate and vinyl ester-acrylatedispersions as additives for building materials. In the case of theseadditives, the flexibility is achieved by means of the, polymercomponent and the use of emulsifiers for stabilizing the emulsion. Anoverview of the present state of the art for flexibilizing buildingcompositions is given in Volkwein, A; Petri, R.; Springenschmid, R;"Protecting concrete by flexible waterproofing slurries",Betonwerk-Fertigteil-Tech. (1988), 54(8) 30-36, 54(9) 72-78.

A disadvantage of the previously used emulsifier-stabilizedstyrene-acrylate dispersions is that they can only be used in2-component systems (component 1=dry mortar, component 2=dispersion),while sufficient flexibilization is not achieved when usingredispersible dispersion powders (in 1-component systems) containing thepresent-day systems (vinyl acetate-ethylene copolymers). However, thegreat advantage of dispersion powders as compared with the dispersionsis that it is possible to produce dry mortar mixtures which only have tobe mixed with water on the building site. This brings many advantagessuch as increased formulation reliability, safe handling and simpledisposal of containers. Up to now, there have been no systems based onemulsifier-stabilized vinyl ester copolymer dispersions available whichhave been able to compete with styrene-acrylate copolymer dispersions interms of flexibility.

DE-A 4206429 (U.S. Pat. No. 5,348,993) discloses binders for improvingthe flexibility of building materials based on vinylpropionate-VeoVa9®(VeoVa10®)¹ emulsion polymers which are prepared inthe presence of an emulsifier combination comprising ethyleneoxide-propylene oxide polyethers, ethoxylated alkylphenol andethoxylated polysaccharide. A disadvantage is that sufficientextensibility is not achieved, for example when used in sealingslurries.

EP-A 527322 discloses additives for cement mixtures which compriseethylene-vinyl acetate-vinyl pivalate copolymers prepared by theemulsion polymerization method in the presence of emulsifier andprotective colloid. The improved alkali resistance compared with vinylacetate-ethylene copolymers is emphasized. A disadvantage is theextensibility which is insufficient for flexibilizing buildingmaterials.

EP-A 518406 discloses the preparation of copolymers of ethylene, vinylacetate and of vinyl esters of α-branched, tertiary carboxylic acidshaving 5 or 9 carbon atoms, with vinyl pivalate (VeoVa5®) beingcopolymerized in place of VeoVa9® to improve the degree of incorporationof ethylene. EP-A 295727 relates to ethylene-vinyl acetate copolymerswith vinyl esters of α-branched tertiary carboxylic acids having 9carbon atoms (VeoVa9®) or 10 carbon atoms (VeoVa10®), with copolymerscontaining VeoVa9® being recommended in place of VeoVa10® for paintshaving reduced tack. The flexibilization of building compositions isdiscussed neither in EP-A 518406 nor in EP-A 295727.

It is an object of the invention to provide copolymers based on vinylester copolymers which are

SUMMARY OF THE INVENTION

it has surprisingly been found that addition of protectivecolloid-stabilized copolymers of vinyl acetate, ethylene and vinylesters of unbranched or branched carboxylic acids having from 5 to 18carbon atoms which have been prepared by the emulsion polymerizationprocess with stabilization using protective colloid provides highlyflexible building compositions which have good strength and asignificantly higher extensibility than building compositions modifiedwith powders based on vinyl acetate-ethylene.

The invention provides flexible, polymer-modified building compositionsbased on mineral binders and one or more vinyl ester-ethylenecopolymers, characterized in that the building compositions containprotective colloid-stabilized vinyl ester-ethylene copolymers obtainableby free-radical, aqueous emulsion polymerization of

a) 15-80% by weight of vinyl acetate,

b) 5-35% by weight of ethylene,

c) 5-60% by weight of one or more vinyl esters of unbranched or branchedcarboxylic acids having from 5 to 18 carbon atoms, and

d) 0-10% by weight of further copolymerizable ethylenically unsaturatedmonomers.

The invention further provides for the use of protectivecolloid-stabilized vinyl ester-ethylene copolymers obtainable byfree-radical, aqueous emulsion polymerization of

a) 15-80% by weight of vinyl acetate,

b) 5-35% by weight of ethylene,

c) 5-60% by weight of one or more vinyl esters of unbranched or branchedcarboxylic acids having from 5 to 18 carbon atoms, and

d) 0-10% by weight of further copolymerizable ethylenically unsaturatedmonomers,

for producing flexible building compositions based on mineral binders.

The percentages by weight are in each case based on the total weight ofthe copolymer.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred comonomers c) are vinyl laurate, vinyl stearate, vinyl2-ethylhexanoate and vinyl esters of α-branched, tertiary carboxylicacids having from 5 to 11 carbon atoms, for example VeoVa5®, VeoVa9®,VeoVa10®, and VeoVa11® (vinyl esters of versatic acid from Shell having5, 9, 10 and 11 carbon atoms). Particular preference is given to thevinyl esters of α-branched, tertiary carboxylic acids having from 9 to11 carbon atoms, for example VeoVa9®, VeoVa10®, or VeoVa11®.

Suitable comonomers d) are, for example, auxiliary monomers forstabilization such as α,β-monoethylenically unsaturated monocarboxylicand dicarboxylic acids and their amides or nitrites, for example acrylicacid, methacrylic acid, acrylamide; ethylenically unsaturated sulphonicacids or their salts, preferably vinylsulphonic acid, 2-acrylamidopropanesulphonate; N-vinylpyrrolidone.

Particular preference is given to vinyl ester-ethylene copolymerscomprising

a) 40-70% by weight of vinyl acetate,

b) 10-30% by weight of ethylene and

c) 20-40% by weight of one or more vinyl esters of α-branched, tertiarycarboxylic acids having 5, 9, 10 or 11 carbon atoms.

The said protective colloid-stabilized vinyl ester-ethylene copolymersare prepared by the free-radical, aqueous emulsion polymerizationprocess, with stabilization using protective colloid. The polymerizationmedium used is preferably water; mixtures of water and water-miscibleliquids can also be used. The polymerization can be carried outbatchwise or continuously, with or without use of seed lattices, withinitial charging of all or individual constituents of the reactionmixture, or with partial initial charging and subsequent metering in allor the other individual constituents of the reaction mixture, or by thefeed stream process without an initial charge. All metered additions arepreferably carried out so as to correspond to the consumption of therespective component(s).

The polymerization is generally carried out in a temperature range from20 to 95° C., preferably from 25 to 65° C. The ethylene pressure isbetween 10 and 85 bar. Initiation is carried out using the water-solublefree-radical formers customarily used for emulsion polymerization, thesebeing preferably used in amounts of from 0.01 to 5.0% by weight, basedon the total weight of monomers. Examples of these are hydrogenperoxide, t-butyl peroxide; alkyl hydroperoxides such as t-butylhydroperoxide; potassium, sodium and ammonium peroxodisulphate; azocompounds such as azobisisobutyronitrile or azobiscyanovaleric acid. Theknown free-radical initiators are preferably combined in a known mannerwith from 0.01 to 1.0% by weight, based on the total weight of themonomers, or reducing agents. Examples of suitable reducing agents arealkali metal formaldehyde sulphoxylate, hydroxymethanesulphinic acid,sodium sulphite and ascorbic acid. In the redox initiation, preferenceis given to metering in one or both redox catalyst components during thepolymerization. In addition, the reactivity of the initiator system canbe increased by addition of metal ions which can occur in a plurality ofoxidation states. Preference is given to using iron(II) ions, forexample in the form of iron(II) sulphate.

Dispersants used for stabilizing the polymerization mixture arepreferably exclusively protective colloids, without addition ofemulsifier; particularly preferably in amounts of from 1 up to 20% byweight, based on the total weight of the monomers. Suitable protectivecolloids are, for example, celluloses such as hydroxyethylcellulose,hydroxypropylcellulose and carboxymethylcellulose; polyvinyl alcohols,polyethylene glycol, polyvinylpyrrolidones, poly(meth)acrylic acid;preference is given to using partially saponified polyvinyl alcohols.Particular preference is given to partially saponified polyvinylalcohols having a degree of hydrolysis of from 75 to 95 mol % and aHoppler viscosity (4% strength solution in water at 20° C.) of from 4 to35 mPas. If emulsifiers are used, their amount should be less than 1.0%by weight, based on the total weight of the monomers.

After the polymerization is complete, the dispersion is adjusted to asolids content of from 30 to 65% by weight, preferably from 45 to 55% byweight. The protective colloid-stabilized vinyl ester-ethylenecopolymers can be added to the building materials in the form of theiraqueous dispersions or preferably in the form of dispersion powdersredispersible in water.

The dispersion powders are preferably produced by means of spray drying.Here, drying is carried out in customary spray drying units, withatomization being able to be carried out by means of one-fluid,two-fluid or multifluid nozzles or by means of a rotary disc.

Before spray drying, the protective colloid-stabilized vinylester-ethylene copolymer dispersion obtained after the emulsionpolymerization is preferably adjusted to a solids content of from 20 to60% The solids content is dependent on the type and amount of furtheradditives which are added in the drying procedure. For example, furtheramounts, preferably from 2 to 20% by weight based on the vinylester-ethylene copolymer, of the abovementioned protective colloid canbe added to the dispersion as atomization aid.

In the atomization, a content of up to 1.5% by weight of antifoam, basedon the copolymer, has often been found to be useful. Liquid antifoamsare normally added to the dispersion before drying, solid antifoams canbe mixed into the dry dispersion powder composition.

The mean particle size of the dispersion powder particles is generallyfrom 10 to 400 μm. The powders redisperse in water to give a dispersionhaving particle sizes between 0.1 and 5.0 μm.

To increase the shelf life by improving the anticaking stability, thepowder obtained can be admixed with an anticaking agent, preferably from3 to 25% by weight based on the total weight of polymeric constituents.Examples of anticaking agents are finely milled aluminium silicates,kieselguhr, colloidal silica gel, pyrogenic silica, precipitated silica,microsilica, light spar, kaolin, talc, cements, diatomaceous earth,magnesium carbonate and/or calcium carbonate or magnesium hydrosilicate.

Further constituents of the dispersion powder composition present inpreferred embodiments are, for example, dyes, fillers, foam stabilizers,waterproofing agents. These constituents can be added before or afterspray drying.

The protective colloid-stabilized vinyl ester-ethylene copolymers areused in the form of their aqueous dispersions or preferably theirdispersion powder compositions for modifying building compositions basedon mineral binders, for example cement, plaster of Paris or lime mortar.Use as dispersion powders is preferred to use of the likewise usableaqueous dispersions since they make it possible to produce dry mortarmixtures which only have to be mixed with water at the building site.

Examples of mineral binders are cements such as Portland cement,aluminate cement, pozzolanic cement, coating cement, magnesia cement andphosphate cement, plaster such as calcium sulphate hemihydrate in theform of building plaster, stucco plaster or modelling plaster and/orlime such as calcium hydroxide. Apart from the mineral binders andwater, the building compositions additionally contain aggregates such assands, for example quartz sand or quartz flour, gravels, chalks,dolomite, light spar, in each case in the particle size and amountcustomary for the respective application. Further examples of aggregatesare fibres such as acrylate, polyethylene or cellulose fibres.

Further additives customary for making up building compositions arethickeners, for example organic thickeners such as cellulose ethers andinorganic thickeners such as bentonite, pigments, wetting agents,dispersants, preservatives, antifoams, film-forming aids and frostprotection agents.

The protective colloid-stabilized vinyl ester-ethylene copolymers arepreferably used for producing highly flexible sealing slurries, buildingadhesives, jointing mortars, repair mortars or crack-bridging plastersand renders. Most preferred is the use for producing highly flexible,cement-containing sealing slurries. A typical dry formulation forsealing slurries is, for example;

from 10 to 50 parts by weight of cement,

from 10 to 50 parts by weight of quartz sand,

from 1.0 to 10 parts by weight of fibres,

from 0.1 to 1.0 part by weight of cement fluidizers and

from 0.1 to 1.0 part by weight of antifoam.

To flexibilize the building compositions, the protectivecolloid-stabilized vinyl ester-ethylene copolymers are preferably usedin an amount of from 10 to 50% by weight, proportion of copolymer basedon the total weight of the dry formulation. The ready-to-use buildingcomposition is produced by mixing with water, with the amount of waterbeing such that from 25 to 60 parts by weight of water are used per 100parts by weight of dry formulation.

When using aqueous dispersions of the protective colloid-stabilizedvinyl ester-ethylene copolymers, the dispersion can be mixed into themortar mixture using the mechanical mixers customary in the buildingindustry. The procedure is advantageously to dilute the dispersion withthe required amount of make-up water and to add it to the mixture ofcement and aggregates and, if desired, further additives. For use in theform of a dispersion powder, the dispersion powder is mixed with theconstituents of the dry formulation and this mixture is mixed with thecalculated amount of make-up water.

The protective colloid-stabilized vinyl ester-ethylene copolymers to beused according to the invention provide for the first time agents basedon vinyl acetate-ethylene copolymers for elastifying buildingcompositions, which agents are in the form of their aqueous dispersionsat least equal to the established styrene-acrylate dispersions but asdispersion powders are significantly superior in respect ofextensibility to protective colloid-stabilized styrene-acrylate andvinyl acetate-ethylene powders. Vinyl acetate-ethylene polymerscustomary hitherto have shown only insufficient extensibility andflexibility for this application, a reason why only styrene-acrylatedispersions have hitherto been used in this application (see Volkwein, Aet al.).

EXAMPLES

Dispersions and dispersion powders to be used according to theinvention:

Dispersion 1:

An aqueous dispersion having a solids content of 51.5% by weight of avinyl acetate-ethylene-VeoVa10 copolymer comprising 56% by weight ofvinyl acetate, 20% by weight of ethylene, 24% by weight of VeoVa10® andhaving a T_(g) of -13° C., which is stabilized with 3% by weight ofpolyvinyl alcohol having a degree of hydrolysis of 88% and a Hopplerviscosity of 4 mPas (4% strength solution in water at 20° C.).

Dispersion 2:

An aqueous dispersion having a solids content of 48% by weight of avinyl acetate-ethylene-VeoVa10 copolymer comprising 46% by weight ofvinyl acetate, 23% by weight of ethylene, 31% by weight of VeoVa10® andhaving a T_(g) of -15° C., which is stabilized with 3% by weight ofpolyvinyl alcohol having a degree of hydrolysis of 88% and a Hopplerviscosity of 4 mPas (4%. strength solution in water at 20° C.).

Dispersion Powders 1 and 2:

To produce the dispersion powders, the abovementioned dispersions 1 and2 were each admixed with 10% by weight, based on polymer, of a polyvinylalcohol having a degree of hydrolysis of 88 mol % and a Hopplerviscosity of 8 mPas and 0.3% by weight, based on polymer, of antifoam.The mixture was spray dried using a two-fluid nozzle. The powderobtained was admixed with 10% by weight of commercial anticaking agent.

Comparative dispersions and comparative dispersion powders not to beused according to the invention,

Dispersion A:

Aqueous, emulsifier-stabilized dispersion having a solids content ofabout 55% by weight of a styrene-acrylate copolymer having a T_(g) of-7° C.

Dispersion B:

Aqueous, emulsifier-stabilized dispersion having a solids content ofabout 50% by weight of a styrene-acrylate copolymer having a T_(g) of-7° C.

Dispersion C:

Aqueous, emulsifier-stabilized dispersion having a solids content ofabout 53% by weight of a styrene-acrylate copolymer having a T_(g) of-40° C.

Dispersion Powders A to D:

To produce the dispersion powders A-D, the corresponding aqueousdispersions were each admixed with 10% by weight, based on polymer, of apolyvinyl alcohol having a degree of hydrolysis of 88 mol % and aHoppler viscosity of 8 mPas and 0.3% by weight, based on polymer, ofantifoam. The mixture was spray dried using a two-fluid nozzle and thepowder obtained was admixed with 10% by weight of commercial anticakingagent.

Dispersion Powder A:

Dispersion powder based on a polyvinyl alcohol-stabilizedstyrene-acrylate copolymer having a T_(g) of -7° C.

Dispersion Powder B:

Dispersion powder based on a polyvinyl alcohol-stabilizedstyrene-acrylate copolymer having a T_(g) of -18° C.

Dispersion Powder C:

Dispersion powder based on a polyvinyl alcohol-stabilizedstyrene-acrylate copolymer having a T_(g) of -40° C.

Dispersion Powder D:

Dispersion powder based on a polyvinyl alcohol-stabilized vinylacetate-ethylene copolymer having a T_(g) of -7° C.

Use Testing:

The dispersion powders were tested in sealing slurry compositions havingthe following formulations I and III. The dispersions were tested insealing slurry compositions having the formulation II.

    ______________________________________                                                         I         II      III                                           (parts (parts (parts                                                          by by by                                                                     Formulation weight) weight) weight)                                         ______________________________________                                        Portland cement PZ 35                                                                          350       350     350                                          Quartz sand F 36 285 285 185                                                  Arbocell BC 1000 (fibres)  20  20  20                                         Melment F 10 (cement  3  3  3                                                 fluidizer)  37  37  37                                                        Tixoton CV 15 (thickener)  5  5  5                                            Agitan P 800 (antifoam) 300 -- 400                                            Dispersion powder -- 600 --                                                   Dispersion (50% solids con- 350  50 350                                       tent)                                                                         Water                                                                       ______________________________________                                    

The constituents of the formulation were mixed dry for 3 minutes in amortar mixer. The water was then added, in the case of the formulationII both the dispersion and the water, and mixing was continued for afurther 2 minutes. After a maturing time of 10 minutes, the mortar wasmixed for 30 seconds and then spread by means of a trowel in a Teflontemplate to give a 2 mm thick sealing coat, after drying it was removedfrom the template and then stored as described in Tables 1, 2 and 3.

After storage, tensile bars were stamped from the sealing coats and thetensile strength and elongation at break of these were determined in atensile test in accordance with DIN 53504 on an Instron tensile testerat an extension rate of 10 mm/min. The mean values of the individualseries of measurements are given in Tables 1 to 3.

In the tables:

d=storage time in days;=storage time in minutes;

SC=storage under standard conditions at 23° C., 50% relative atmospherichumidity;

wet=wet storage at 23° C. in water;

0° C.=storage at 0° C., 50% relative atmospheric humidity.

The measured values are given in the table as follows: elongation atbreak [%]/tensile strength [N/mm² ].

                  TABLE 1                                                         ______________________________________                                        (Power according to formulation I):                                             Storage A       B      C      D     1      2                                ______________________________________                                        28d SC                                                                              5.6/2.2 5.1/2.8  4.5/-- 13.3/4.3                                                                            30.7/3.4                                                                             32.4/2.1                             28d SC 5.5/2.1 5.9/1.1 7.2/0.8 12.9/4.9 12.4/1.2 14.6/0.9                      7d wet                                                                       28d SC 1.5/4.4 3.5/3.7 2.1/3.9  9.8/0.9 23.0/3.8 18.5/3.5                     14d wet                                                                       14d SC                                                                        28d SC --/-- 5.4/10.5  2.1/11.0  --/--  6.3/10.4 14.9/6.8                     30'                                                                           0° C.                                                                ______________________________________                                    

The sealing slurries modified with the powders 1 and 2 (polyvinylalcohol-stabilized vinyl acetate-ethylene-VeoVa10® polymers) displaysignificantly better elongation at break, while retaining the tensilestrength, than polyvinyl alcohol-stabilized styrene-acrylate powders(powders A, B, C) or polyvinyl alcohol-stabilized vinyl acetate-ethylenepowders (powder D).

                  TABLE 2                                                         ______________________________________                                        (Power according to formulation III):                                           Storage A       B      C      D     1      2                                ______________________________________                                        28d SC                                                                              9.9/2.0 10.2/2.7 8.7/-- 19.4/3.9                                                                            57.2/3.4                                                                             67.1/1.9                             28d SC 9.0/1.9 9.8/0.9 11.2/0.7  21.3/0.6 48.3/1.0 47.2/0.8                    7d wet                                                                       28d SC 2.6/4.4 5.9/3.9 3.3/4.1 14.4/3.8 63.7/3.5 62.6/3.3                     14d wet                                                                       14d SC                                                                        28d SC --/-- 10.8/10.7  4.1/11.7  --/--  18.1/10.7 29.6/7.6                   30'                                                                           0° C.                                                                ______________________________________                                    

A similar result to Table 1 was obtained:

The sealing slurries modified with the powders 1 and 2 (polyvinylalcohol-stabilized vinyl acetate-ethylene-VeoVa10® polymers) displaysignificantly better elongation at break, while retaining the tensilestrength, than polyvinyl alcohol-stabilized styrene-acrylate copolymers(powders A, B, C) or polyvinyl alcohol-stabilized vinyl acetate-ethylenepowders (powder D).

                  TABLE 3                                                         ______________________________________                                        (Dispersion according to formulation II):                                       Storage  A       B      C      1       2                                    ______________________________________                                        14d SC 62.2/2.5                                                                              35.1/3.9 37.5/2.0                                                                             115.0/2.5                                                                             113.0/1.6                                14d SC 39.4/0.7 39.3/0.7 36.7/5.7 34.1/--  44.3/0.6                            7d wet                                                                       14d SC 59.4/2.5 27.2/5.1 27.4/2.1 58.1/2.8 80.8/1.8                            7d wet                                                                        7d SC                                                                      ______________________________________                                    

The use according to the invention of the protective colloid-stabilizedvinyl ester-ethylene copolymers in the form of their aqueous dispersions(dispersion 1 and 2) effects an elastification of the buildingcompositions which in respect of the extensibility is at least equal(dispersion a) or significantly superior (dispersions b, c) to theconventional emulsifier-stabilized styrene-acrylate dispersions.

What is claimed is:
 1. Flexible, polymer-modified building compositionsbased on mineral binders wherein the building compositions containprotective colloid-stabilized vinyl ester-ethylene copolymers consistingessentially of copolymers obtainable by free-radical, aqueous emulsionpolymerization ofa) 15-80% by weight of vinyl acetate, b) 5-35% byweight of ethylene, c) 5-60% by weight of one or more vinyl esters ofα-branched carboxylic acids having 9-11 carbon atoms, and d) 0-10% byweight of further copolymerizable ethylenically unsaturated monomers,with the proviso that no emulsifier is contained in the buildingcomposition.
 2. A process for the preparation of a flexible, polymermodified building composition based on mineral binders which comprisesadding to a mineral binder composition, a protective colloid stabilizedvinylester ethylene copolymer, which contains no emulsifier, andconsists essentially of a copolymer being in the form of an aqueousdispersion or re-dispersible powder and obtained by free-radical,aqueous emulsion polymerization ofa) 15-80% by weight of vinyl acetate,b) 5-35% by weight of ethylene, c) 5-60% by weight of one or more vinylesters of α-branched carboxylic acids having 9-11 carbon atoms, and d)0-10% by weight of further copolymerizable ethylenically unsaturatedmonomers.
 3. Claim 1, wherein the comonomers c) are selected from thegroup consisting of vinyl laurate, vinyl stearate, vinyl2-ethylhexanoate and vinyl esters of a branched, tertiary carboxylicacid having from 5 to 11 carbon atoms.
 4. Claim 1, wherein the vinylester-ethylene copolymers used comprisea) 40-70% by weight of vinylacetate, b) 10-30% by weight of ethylene and c) 20-40% by weight of oneor more vinyl esters of α-branched, tertiary carboxylic acids having 9,10 or 11 carbon atoms.
 5. Claim 1, wherein the protective colloidspresent are partially saponified polyvinyl alcohols having a degree ofhydrolysis of from 75 to 95 mol % and a Hoppler viscosity (4% strengthsolution in water at 20° C.) of from 4 to 35 mPas.
 6. Claim 1, whereinthe protective colloid-stabilized vinyl ester-ethylene copolymers areadded in the form of their aqueous dispersions to the buildingmaterials.
 7. Claim 1, wherein the protective colloid-stabilized vinylester-ethylene copolymers are added in the form of dispersion powdersredispersible in water to the building materials.
 8. Claim 1, whereinthe building compositions belong to the group consisting of sealingslurries, building adhesives, jointing mortars, repair mortars,crack-bridging plasters and renders.
 9. Claim 1, wherein the protectivecolloid-stabilized vinyl ester-ethylene copolymers are present in anamount of from 10 to 50% by weight, proportion of copolymer based on thetotal weight of the dry formulation.
 10. The process of claim 2 whereinthe copolymer is in the form of a redispersible powder.
 11. The processof claim 2 wherein the copolymer is obtained by free-radical aqueousemulsion polymerization ofa) 40-70% by weight of vinyl acetate, b)10-30% by weight of ethylene and c) 20-40% by weight of at least onevinyl ester of a branched, tertiary carboxylic acid having 9, 10 or 11carbon atoms.
 12. The process of claim 2 wherein the protective colloidsare partially saponified polyvinyl alcohols having a degree ofhydrolysis of from 75 to 95 mol % and a Hoppler viscosity (4% strengthsolution in water at 20 C) of from 4 to 35 mPas.
 13. The process ofclaim 2 wherein the flexible, polymer-modified building compositions arein the form of sealing slurries.
 14. The process of claim 2 wherein themineral binder composition is comprised of:from 10 to 50 parts by weightof cement, from 10 to 50 parts by weight of quartz sand, from 1.0 to 10parts by weight of fibres, from 0.1 to 1.0 parts by weight of cementfluidizers and from 0.1 to 1.0 parts by weight of antifoam.